Jerry Gilfoyle Shroud 1 / 11 How Old is the Shroud of Turin? What - PowerPoint PPT Presentation

Jerry Gilfoyle Shroud 1 / 11

How Old is the Shroud of Turin? What is the Clock? Jerry Gilfoyle Shroud 2 / 11

How Old is the Shroud of Turin? What is the Clock? Mass Spectrometry Jerry Gilfoyle Shroud 2 / 11

How Old is the Shroud of Turin? What is the Clock? Mass Spectrometry Radiocarbon Dating. Jerry Gilfoyle Shroud 2 / 11

Mass Spectrometry A Mass Spectrometer Sputter Source Detectors B out Jerry Gilfoyle Shroud 3 / 11

Radiocarbon Dating Carbon Ratios 12 13 14 6 C 6 C 6 C Cosmic ray proton 98.89% 1.11% 10 − 9 Reaction Chain 14 N Atmosphere 14 7 N + 1 1 H → 14 8 O + 1 0 n neutron 7 N + e + + ν proton 14 8 O → 14 14 N 14 14 7 N + 1 0 n → 14 6 C + 1 C 1 H O 2 14 CO 2 6 C + e + + ν 14 7 N → 14 dead or buried material 14 loses C Jerry Gilfoyle Shroud 4 / 11

How Old is the Shroud? The radioactive isotope 14 C decays via A - Arizona O - Oxford 14 C → 14 N + β − + ν Z - Zurich where β − is an electron and ν is a par- ticle called the neutrino. The ratio R = 14 C / 12 C was measured in 1989 to deter- mine the age of the shroud. The results are shown here. The shroud is sample 1. The other samples are controls. Ages Nature 337, no. 16 p 611 (1989) are in years BP (before 1950). Note the break in the age scale. Laboratory R How old is the shroud? The typical 1 . 20 × 10 − 12 Arizona uncertainty in these measurements is 1 . 18 × 10 − 12 about 40 years. Are the results of the Oxford 1 . 19 × 10 − 12 three labs consistent? Zurich Jerry Gilfoyle Shroud 5 / 11

Geiger-Muller Tube A Geiger-Muller tube (or GM tube) is the sensing element of a Geiger counter instrument that can detect a single particle of ionizing radiation. It is a type of gaseous ionization detector with an operating voltage in the Geiger plateau. Jerry Gilfoyle Shroud 6 / 11

Radiocarbon Calibration Curve Jerry Gilfoyle Shroud 7 / 11

Radioactive Decay 14 C decay 137 Ba decay Jerry Gilfoyle Shroud 8 / 11

The Age of the Earth The figure below shows the decay scheme for 238 U which can be approximated as 238 U → 206 Pb + other decay products where the half-life is determined by that first step. Why? A rock is found containing m U = 0 . 0042 kg of 238 U and m Pb = 0 . 0024 kg of 206 Pb . Assume the rock contained no lead at all when it was formed so all the lead present is from the decay of uranium. What is the age of the rock? What does this say about the age of the Earth? 238 α 234 β 234 β 234 α 230 α U Th Pa U Th 92 90 91 92 90 9 5 4 4.5x10 y 24 d 6.7 h 2.5x10 y 7.4x10 y 226 α 222 α 218 α 214 β 214 β Ra Rn 84 Po Pb Bi 88 86 82 83 1600 y 3.8 d 3.1 m 27 m 20 m 214 α 210 β 210 β 210 α 206 84 Po Pb Bi 84 Po Pb 82 83 82 0.16 ms 22 y 5.0 d 138 d Jerry Gilfoyle Shroud 9 / 11

The Periodic Chart Jerry Gilfoyle Shroud 10 / 11

How Old is the Shroud? The radioactive isotope 14 C decays via A - Arizona O - Oxford 14 C → 14 N + β − + ν Z - Zurich where β − is an electron and ν is a par- ticle called the neutrino. The ratio R = 14 C / 12 C was measured in 1989 to deter- mine the age of the shroud. The results are shown here. The shroud is sample 1. The other samples are controls. Ages Nature 337, no. 16 p 611 (1989) are in years BP (before 1950). Note the break in the age scale. Laboratory R How old is the shroud? The typical 1 . 20 × 10 − 12 Arizona uncertainty in these measurements is 1 . 18 × 10 − 12 about 40 years. Are the results of the Oxford 1 . 19 × 10 − 12 three labs consistent? Zurich Jerry Gilfoyle Shroud 11 / 11